Flat panel type image display devices such as a liquid crystal, plasma, organic EL, etc., are of special interest in the marketplace. The flat panel type image display device has a display area (an image display portion) in which a number of picture elements comprising a semiconductor layer or a fluorescent layer constituting an active element, or a light-emitting layer are provided in a matrix state between a pair of the substrates at least one of which has optical transparency such as a glass. The devices are generally formed by encapsulating the surroundings of the display area (an image display portion) and a protective portion formed by a glass or an optical plastic such as an acrylic resin by an adhesive.
Current flat panel displays employ liquid optically clear adhesives in between various functional layers to effectively fill the air-gap for proper light management and mechanical integrity of the overall device. Silicone adhesives offer an advantage over the traditional epoxy or organic acrylic systems mainly with respect to their mechanical stability over a wide range of temperature, low shrinkage properties, and ability to offer low mura characteristics. Typical industrial demands for these optically clear adhesives include fast dual cure characteristics such as UV and/or moisture cure to address curing both in transparent regions and in regions under the black matrix of the device while offering low modulus, high reliability, and no delamination.
The major challenges in the development of silicone formulations involve the attainment of proper dissolution of several additives in one-part formulations to achieve optical clarity, fast cure speed, low modulus, and a high reliability material.